This invention relates generally to ratchet mechanisms and more particularly to a reversible ratchet head assembly.
Reversing ratchet mechanisms are widely employed in both hand and powered tools. Some tools employ a combination of powered and manual operation. In those tools, for manual operation, a ratchet mechanism is used so that the tool works like a conventional manual ratchet tool. All ratcheting mechanisms use a pawl engageable with ratchet teeth to fix the tool and an output shaft together for conjoint rotation in one direction and to permit relative rotation of the tool relative to the output shaft in another, opposite direction. The direction in which relative rotation is permitted and prevented can be reversed by changing the position of the pawl. Reversal is typically achieved in hand tools, and also in many powered tools, by turning a knob to move the pawl to a different position. Conventionally, the direction the knob is turned is opposite to the direction in which the output shaft will be driven when the tool is used. Thus, there can be some confusion for the operator as to which way to turn the knob because the knob is turned in the direction opposite the direction of the desired driving rotation of the output shaft. An example of a powered tool having such a ratchet reversing mechanism is shown in U.S. Pat. No. 3,529,498. The tool shown in this patent uses an oscillating yoke connected to an output shaft through the pawl.
Certain powered tools reverse the direction of the pawl automatically when the direction of the motor is reversed. An example of such an automatic ratchet reversing mechanism is shown in my U.S. Pat. No. 5,562,015, the disclosure of which is incorporated herein by reference. My prior tool is of the type which permits manual ratcheting operation of the tool when the resistive torque of the fastener being tightened or loosened is greater than can be overcome by the motor. The tool can be turned manually to supply a greater torque to the fastener to overcome its resistence. The position of the pawl is changed by axial movement of a pawl reverser gear (25) which briefly engages a pawl (35) to toggle it from one position to another. The axial movement of the pawl reverser gear is actuated by a change in direction of the motor and the direction in which the pawl is toggled is controlled by the direction of rotation of the motor. The different positions of the pawl permit driven rotation in different directions during manual operation of the tool. The operation of this tool has been most satisfactory. However, the reversing mechanism does require some space within the housing to allow for axial movement of the pawl reverser gear. Accordingly, it would be desirable to have an automatic reversing mechanism of a more compact configuration.
Among the several objects and features of the invention may be noted the provision of a reversible ratcheting head assembly which is compact in construction; the provision of such a reversible ratcheting head assembly which is capable of operation at higher speeds; the provision of such a reversible ratcheting head assembly which can be directly driven by a motor; the provision of such a reversible ratcheting head assembly which clearly indicates to the operator the direction of driven rotation upon changeover of the direction of driven rotation; and the provision of a ratcheting head assembly which is economical to manufacture and easy to use.
Further among the several objects and features of the present invention may be noted the provision of a powered tool having the features set forth above.
Generally, a reversible ratchet head assembly comprises a head and ratchet teeth disposed internally of the head. A reversal actuator mounted for rotation in the housing is attached to an output shaft assembly in the head for rotation of the reversal actuator relative to the output shaft assembly. The output shaft assembly further comprises a ratchet pawl pivotally mounted on the output shaft assembly and engageable with the ratchet teeth on the head. The pawl is pivotable between a first position in which the pawl engages the ratchet teeth to hold the output shaft assembly and head together for conjoint rotation in a first direction and to permit relative rotation between the output shaft assembly and the head in a second direction, and a second position in which the pawl engages the ratchet teeth to hold the output shaft assembly and head together for conjoint rotation in the second direction and to permit relative rotation between the output shaft assembly and the head in the first direction. The reversal actuator is constructed to engage the pawl upon rotation of the reversal actuator relative to the output shaft assembly in the first direction to move the pawl to the first position and constructed to engage the pawl upon rotation of the reversal actuator relative to the output shaft assembly in the second direction to move the pawl to the second position.
In another aspect of the present invention, a powered tool capable of operating as a manual ratchet tool generally comprises a housing including a head and ratchet teeth disposed internally of the head, and a reversible motor in the housing. A reversal actuator mounted in the housing is operatively connected to the motor to be driven in rotation by the motor. An output shaft assembly generally in the head of the housing is attached to the reversal actuator for rotation of the reversal actuator relative to the output shaft assembly in a first direction over an arc and for conjoint rotation with the reversal actuator in the first direction after rotation over the arc in the first direction, and for rotation of the reversal actuator relative to the output shaft assembly in a second direction opposite the first direction over the arc and for conjoint rotation with the reversal actuator in the second direction after rotation over the arc in the second direction. Thus, the attachment of the output shaft assembly to the reversal actuator allows rotation of the reversal actuator relative to the output shaft assembly over the arc to occur upon reversal of the motor. The output shaft assembly further comprises a ratchet pawl pivotally mounted on the output shaft assembly and engageable with the ratchet teeth on the head. The pawl is pivotable between a first position in which the pawl engages the ratchet teeth to hold the output shaft assembly and head together for conjoint rotation in one direction and permit relative rotation between the output shaft assembly and the head in another direction opposite said one direction, and a second position in which the pawl engages the ratchet teeth to hold the output shaft assembly and head together for conjoint rotation in said other direction and to permit relative rotation between the output shaft assembly and the head in said one direction thereby to permit manual ratcheting operation of the tool. The reversal actuator is adapted to engage the pawl for pushing the pawl between said first and second positions upon relative rotation between the output shaft assembly and the reversal actuator whereby manual ratcheting is automatically reversed upon reversal of the motor.
Other objects and features of the present invention will be in part apparent and in part point out hereinafter.